This invention relates to improved means for shaping the leading and trailing edges of integrally cast blades used in aircraft gas turbine engines. In making a compressor rotor, for example, it is aerodynamically important that the blade edges have a small radius of curvature in order to achieve efficient operation. By small is meant that the radius on the leading and trailing edge of a compressor blade be in the range of 0.007 to 0.012 inch. In practice it has been difficult to maintain this sort of dimensional tolerance in the casting process. As a result, it has been common practice to cast the blade edges slightly oversize and then machine to specifications by a milling or grinding process. Since adjacent blades are often less than a half inch apart, it becomes a problem to design cutting tools which are capable of trimming one blade without bumping into adjacent blades. Additionally, the blades themselves may have compound contours which would complicate the tooling problem.
In this environment it has been found advantageous to utilize electro-chemical milling. Using my invention an entire blade can be shaped quickly to close tolerances. Test results show that with my apparatus it is possible to shape a blade in less than a minute. This includes loading and clamping the fixture, milling the blade to size, unclamping the fixture and indexing to the next position.